1. Field of the Invention
The present invention relates generally to the fields of equipment for aiding the disabled and to medical equipment. More specifically the present invention relates to a wheel chair having a lever arm propulsion mechanism and a collapsible frame with spaced apart first and second wheels, the wheels being affixed to first and second wheel half-axles. The propulsion mechanism includes first and second clutches secured to corresponding first and second wheel half-axles. Each clutch has an outer clutch drum which engages and rotates an internal clutch core affixed to the given half-axle when rotated in one direction and disengages the core and spins freely about the core when rotated in the opposing direction. A lever arm is pivotally mounted to the frame and is affixed to a lever arm axle fitted to a drive cable pulley, and a drive chain or cable is engagingly wrapped around the drive cable pulley and engagingly wrapped twice around the first clutch drum. The cable extends from the first clutch drum engagingly around a reversing pulley rotatably mounted on a pulley stem secured to the frame, and from the reversing pulley is engagingly wrapped twice around the second clutch drum in the opposite direction from its winding around the first clutch drum, and then returns to the drive cable pulley to form a closed cable loop.
Rotation of the first and second clutch drums about the wheel half-axle in opposing rotational directions causes the first clutch to drive the wheel axle in a forward rotational direction while second clutch does not engage, and rotation of the first and second clutch drums about the wheel axle in reversed opposing rotational directions causes the second clutch to drive the wheel axle in a forward rotational direction while the first clutch does not engage. As a result of this construction, pivoting the lever arm in a forward direction rotates the first clutch drum in a first rotation direction and thereby drives the wheel half-axle and wheel forwardly, and pivoting the lever arm in the opposite, second rotational direction continues to drive the wheel half-axle and wheel forwardly. Thus no movement of the lever arm is wasted, and maximum efficiency is achieved because all movement of the lever arm causes forward wheel half-axle and wheel rotation.
2. Description of the Prior Art
There have long been wheel chairs for mobilizing the injured and disabled, either under the power of an assistant pushing the chair or under the power of the chair occupant or user. In the latter instance, prior art wheel chairs have been highly inefficient because the user typically has to grip an outer ring on the side of a chair wheel and rotate the wheel a few degrees, slide the hand back and rotate it a few more degrees. This is inefficient because half of the hand movement, that is, sliding the hand back to begin rolling the wheel again, delivers no propelling drive to the wheel. Another problem is that the arm and chest muscles must be exerted while the arms are in an awkward position, causing soreness and fatigue. Still another problem has been that the chairs collapse inefficiently and have two forward caster wheels, making turning a high friction-resistance exercise.
It is thus an object of the present invention to provide a wheel chair which can be powered by hand with the arms in a comfortable and maximized muscle power delivery position.
It is another object of the present invention to provide such a wheel chair which delivers muscle power to the wheels throughout the entire arm motion cycle, so that speed and efficiency are maximized.
It is still another object of the present invention to provide such a wheel chair which folds compactly and efficiently, and which has only one, central forward caster wheel, so that turning friction from rotating the caster wheel axle structure is minimized.
It is finally an object of the present invention to provide such a wheel chair which is relatively inexpensive to manufacture and is sturdy and reliable.